1. Field of the Invention
This invention relates to a button telephone equipment to execute the. line exchange by using a plurality of button telephone apparatus having public line buttons containing a communication line.
2. Description of the Related Art
A conventional button telephone equipment having a plurality of button telephone apparatus can indicate an incoming call status on a public line button of the button telephone apparatus, the public line button containing a plurality of telephone lines.
According to this button telephone equipment, the button telephone apparatus can receive the incoming call by depressing the public line button of indicating the incoming call status and can send the outgoing call by depressing the public line button in the unused status. Further, when the user of the button telephone apparatus transfers the telephone line to another button telephone apparatus, the button telephone apparatus makes the public line button in the holding status by holding the telephone line by the holding operation and can receive the holding of the telephone line in the holding status by depressing the public line button of indicating the holding status.
However, according to this conventional button telephone equipment, on the reception of the incoming call, the user can not identify the sender's name without receiving the incoming call. Also, on the reception of the holding, the transfer transfers the telephone line to another button telephone apparatus after telling the sender's name to the user of the another button telephone apparatus. However, when the user can't hear the sender's name from the transfer, he can not identify the sender's name without receiving the holding.
Recently, the service of the sender's telephone number notification began. According to this service, the conventional button telephone equipment can display the sender's telephone number on the display of the button telephone apparatus and display the sender's name on the basis of the sender's telephone number. However, when having a plurality of the incoming call line or the holding line, the button telephone apparatus can't display all sender's number or name with respect to the incoming call line or the holding line on the display. Therefore, the user can't recognize all the sender's name with respect to the incoming call line or the holding line.
Also, in order to solve these above-mentioned problems, it is generally known to use the telephone apparatus provided with a large display for displaying the plurality of the sender's telephone number and to provide a display separate from the button telephone apparatus.
However, this has a drawback in that the button telephone apparatus must provide newly the display which causes too high cost. In order to solve these above-mentioned problems, this invention is to provide the button telephone equipment that can display all sender's information before receiving the incoming call or the holding, even if having simultaneously a plurality of the incoming call line or the holding line.